1. Field of the Invention
The present invention relates to a disk drive device.
2. Description of the Related Art
Disk drive devices like a hard disk drive that is a kind of a rotating device employ a structure in which a disk retaining space defined by a chassis and a top cover and for retaining a recording disk is filled with clean gas. According to such disk drive devices, a bearing mechanism is fastened to a through-hole provided in the chassis in some cases, and in this case, there is a concern about, for example, a leak-out of the clean gas and a leak-in of unclean gas from a space of the joined portion between the through-hole and the bearing mechanism.
Hence, JP 2012-089199 A and JP 2012-104169 A disclose a disk drive device that has the bearing mechanism fastened to a recess with a bottom formed in the chassis in order to suppress a leak-out of the clean gas and a leak-in of unclean gas.
According to such a disk drive device, after predetermined components are assembled with the chassis, gases present in the disk retaining space is discharged, and a filling gas having different composition and cleanness from those of the already-present gas is filled in the disk retaining space. An example already-present gas is air, while an example filling gas is a gas having a relatively small molecular weight, such as helium or a hydrogen gas.
However, the already-present gas in a substantially closed space like a space between the recess with a bottom of the chassis and the bearing mechanism in the axial direction is discharged through a tiny gap of the joined portion between the recess with the bottom and the bearing mechanism. Accordingly, it takes a long time to sufficiently discharge the already-present gas. When the filling gas is charged without having the already-present gas in the substantially closed space to be sufficiently discharged, the remaining already-present gas leaks to the disk retaining space as time advances, contaminates the filling gas, thereby changing the characteristics of the filling gas. When the characteristics of the filling gas change, in the worst case, the floating level (gap) of the magnetic head relative to the recording disk changes, resulting in a malfunction of the disk drive device.
The present invention has been made in view of the above-explained disadvantages, and it is an object of the present invention to provide a disk drive device which suppresses a mixing of an already-present gas with a filling gas, and which is capable of suppressing an occurrence of a malfunction.